The present disclosure relates to a method for reducing the excitation amplitudes in order to improve turbine blade durability and to turbomachinery created using the method.
Some engines are subjected to a number of unscheduled removals due to the effects of high cycle fatigue on certain turbine blades. One contributor to this is a nozzle vane trailing edge at an extreme end of the manufacturing dimensional tolerance, which generates a forcing function whose amplitude exceeds an intended design limit.
In another engine, the cause of a radial turbine scallop failure was traced back to the resonance of the blade excited by the turbine nozzle vanes. Broken turbine fragments travel through the exhaust assembly resulting in an uncontained exit. The strong amplitude of the excitation force leads to blade dynamic stresses exceeding the material strength capability.
There remains a need for a way to reduce excitation amplitudes so as to improve turbine blade durability.